//导入fs模块
const fs = require('fs')

//构建一个读取文件的函数
function readFile(){

    //构建的promise对象将异步代码同步化
    return new promise((resolve,reject)=>{

        //异步代码读取文件
        fs.readFile(path, (err,data)=> {
            if(!err) {
                resolve(data)
            } else{
                reject(err)
            }
        })
    })       
}
readFile("./1.txt")
//箭头函数写法
.then(res => {
    console.log("读取到的结果是"+res);
})

.catch(err => {
    console.Log(err);
})

readFile("./2.txt")
.then(res => {
    console.log('误取到的结果是'+res);
})
//完成了写入文件时函数的封装
function writeFile (path,content){

new promise((resolve, reject) => {
    fs.writeFile(path,content,err => {
        if(!err){
            resolve()
        }else{
            reject(err)
        }
    })
})
}
writeFile('./1.txt','hhh')
.then (res => {
    console.log(res);
})
.catch (err => {
    console.log(err);
})
writeFile('./2.txt','12345')